Not sure if this srtill works, but i wrote it down many, many, many, many years ago. maybe worth trying...
In some rare cases customers may have requirement for SCN features (BLF, extn dialling, directory sharing) but not have the bandwidth to facilitate calls across the link too.
By default, the IPO will force all extn/SCN calls down the SCN trunk, but it is possible to disable this and route voice traffic over the PSTN whilst maintaining a SCN link for the other functions.
BYPASS
Create the SCN link as normal, but set the number of channels to 1 and the number of outgoing channels to 0.
Create a new ARS entry called **NET**
Include the shortcodes needed to match extns. Should be able to use wildcards (not tested it).
FALLBACK
As above for the ARS tables, but the leave the channels as normal. If the system can't route to an extn because the SCN link is down, it then looks for the **NET** ARS Table.
APSS/ACIS/ACSS-SME
not arrogant, just succinct.